In recent years, a number of electric vehicles such as battery electric vehicles (BEV; may be called electric cars) or plug-in hybrid vehicles (PHV) have been put to practical use. Driving batteries installed on such electric vehicles are electrically charged, for example, by power supplied from a commercial power supply, such as a domestic power supply, via a charging cable connected to a charging inlet of a vehicle body.
Methods for controlling charging include, for example, constant current charging by which the driving battery is charged at a constant current, constant voltage charging by which it is charged at a constant voltage, and constant power charging by which it is charged at a constant power. Various charging control methods comprising combinations of these methods are proposed. Concretely, the method in common use comprises performing constant power charging in which the electric energy is rendered constant in the initial stage of charging; terminating the constant power charging when the state if charge (SOC) of the driving battery rises to bring the voltage to a predetermined value; and, at this time, performing constant voltage charging for charging at a constant voltage (see, for example, Patent Document 1).